Electromyography (EMG) has been used to study the factors that contribute to changes in strength that occur over the time course of a training period. EMG records muscle action potentials and is an indicator of the recruitment of muscle fibers. Mechanomyography (MMG) is the recording of lateral vibrations produced by muscle. It has been suggested that MMG reflects the intrinsic property of muscle contraction, independent of electrical activity. MMG may be a useful tool, therefore, for the evaluation of the mechanical changes that occur with strength training. The purpose of the present study was to monitor the EMG and the MMG in the thigh over the course of a twelve week muscular training program. Twelve male subjects performed leg extensions three days per week for twelve weeks. Every four weeks strength, EMG, and MMG activity were measured in the thigh. The strength measures increased, however the EMG and MMG did not change over the course of the training period. The reason for the increase in strength without a change in EMG or MMG may be due to changes in other muscle groups involved in leg extension movements
